Swapping carbs, maybe Holley Street Avenger?

Distributor is a stock replacement from O'reilly. about 4 years old with maybe 4000 miles on it.

 

Well, got on the phone with Holley Tech Support and answered a bunch of questions and the guy says that since it has no part numbers where they are supposed to be, it is a Proform brand carb. They use the holley "end pieces" and metering blocks and their own main housing.

Anyways, he said to push my throttle back to where the secondaries are just getting ready to open, then as soon as they start to move, I should get a pump squirt. It didn't squirt until they were about half open. So he told me to back off the nut with the upright spring near the rear fuel inlet (far left in the first picture), and that will get the pump to squirt sooner. I now have it almost there. Still a little hesitation, but I think a little more adjustment and it will be dead on.

Just have to wait until the school buses stop running. I don't want to sit behind them out on country back roads when I should be attempting to pop wheelies with my new carb....

 

Stick with one thing at a time an get it the best you can. Glad carb is coming around! Just wondering,,,what is your total timing with vacuum hooked up? Run rpm's to 3,000 and see what the timing marks show with light

 

Was 38 with the last carb. Not sure what it is with this one, if it may have changed, wouldn't think so. Loaned my timing light out to a neighbor (2 months ago) this would be a good excuse for me to ask for it back...

 

The proper way to adjust the pump lever arm is to have .015" clearance between the screw/nut and the pump arm with the arm fully depressed and the throttle fully open. Keeps from damaging the pump diaphram at full stroke.

 

Well, not really. Ported vacuum increases as the throttle blades open, manifold vacuum decreases as the throttle opens. One requires a whole different ignition timing curve than the other.

 

Still has a little hesitation but drives much better.

I really need to find someone who knows how to mess with these carbs, meet them somewhere we can run hard and fast, and screw with it there.

Times like these it sucks to live out in the middle of nowhere...

 

Just so you know,that's not a Proform body.That looks to me to be a List#4779 750 with the choke horn removed.Hows it running now when you ''Mash the pedal''? I don't run any vacume advance just plugged off at the carb and 32 deg total timing at 3000 rpm. I have a similar cam at 512 lift 280 duration.

 

It runs half decent with the throttle mashed. Still a little hiccuping. I may do the 32 total timing and take of the vacuum. See what happens.

So, Derek, is this the same carb you are running? If so, any ideas where I can get some tuning instructions?

For now, I put my edelbrock back on and put the acc pump on as sensitive as possible so it hits full blast early on. And it is running better than it was, and better than the Holley. Just kinda messing with each to see which I can get to run best.

 

Definately not a Proform, it's a Holley with the choke horn milled off. The exact size can only accurately determined by measuring the throttle blades and throat diameter. Try removing any slack between the accellerator pump arms and the pump cam levers, should be zero clearance there.

 

Tuning a holley can be a bit tricky but not real hard.And to say "this is how to set them up" doesn't apply to everyones car.Anyhow I have a Holley of just about every size 600-850.I generally found the 650 to work best on my car,with the air mixture screws turned out just till the engine is at it's highest idle rpm and i have the pumps set a little tight [ no slop] Right now i need to jet up the primary side because just like your car it starts to miss a little just before the secondarys are going to open.I know it needs more jet because i already improved it by increasing the jets by 2 sizes.
Also check your float levels the fuel should just start to trickle out once you remove the float bowl sight screw.If it's too low you might be running the bowl out of fuel once the engine demands more fuel
The best suggestion i have right now is to do a internet search for tuning tips.I'll see if i come up with anything for ya.

 

There are several good books available about tuming Holeys for around $20 each.

Some links I saved:

http://www.stockcarracing.com/techarticles/scrp_0508_carburetor_cures/

http://www.bob2000.com/carb.htm

http://www.mortec.com/carbs.htm

http://www.holley.com/TechService/Library.asp